This invention relates to the design and use of microfluidic devices, particularly microfluidic valves, pumps and mixers.
Microfluidic devices are used extensively in biotechnology and health industries for the manipulation and analysis of small quantities of fluid samples. Various devices have been proposed for use as valves and pumps, such as described in U.S. Pat. No. 6,146,103 to Lee et al issued Nov. 14, 2000, and U.S. Pat. No. 6,056,269 to Johnson et al issued May 2, 2000. The Lee et al device provides a valve for a microfluidic device, but the design described requires a somewhat complicated structure and as shown does not show how to prevent leakage. The Johnson et al device provides a device that blocks flow by movement of a plate parallel to fluid flow. Again this device has a somewhat complicated design. This invention is directed to an improved microfluidic control device that is easy to make and use, while ensuring a tight fluid seal in a microfluidic flow control structure.
There is therefore provided according to an aspect of the invention, a method of controlling fluid flow in a channel in a microfluidic flow control device. The method may comprise introducing fluid to the channel, with the fluid flowing in a flow direction and controllably deforming material defining the channel in a direction perpendicular to the flow direction to control fluid flow in the channel. The channel is preferably formed between a first plate and a second plate and controllably deforming material defining the channel comprises deforming at least one of the first and second plates. Preferably, material defining the channel extends continuously between an inlet port and an outlet port. Controllably deforming material defining the channel preferably comprises deforming the first plate into contact with a seat formed in the second plate to close the channel. The seat may be formed by a ridge having a smoothly changing profile in section across the channel.
A pumping action may be obtained by deforming the channel at successively at spaced apart positions along the channel to drive fluid along the channel. Alternatively, a pumping action may be obtained by closing the channel at a first position by deformation of the channel, compressing the channel in a compression region adjacent the first position to drive fluid in the channel along the channel away from the first position past a second position in the channel, closing the channel at the second position by deformation of the channel to prevent fluid flow past the second position into the compression region while the compression region is decompressed; and opening the channel at the first position to allow fluid to flow into the compression region while the compression region is decompressed.
A filtering action may be obtained, for particular use when the fluid contains particles, by controllably deforming material defining the channel to restrict the channel sufficiently to selectively prevent and allow the particles to move with the fluid in the channel.
According to a further aspect of the invention, there is provided a microvalve, comprising a first plate and a second plate placed together to form a channel between them, valve seat formed in the first plate on one side of the channel, the valve seat having a valve seat profile, and the second plate being deformable opposite to the valve seat into a deformation profile that matches the valve seat profile. Preferably, the valve is actuated by an actuator positionable against one of the first plate and the second plate for deforming the one of the first plate and the second plate. The valve seat is preferably formed by a ridge extending transversely across the channel. Preferably, the ridge drops in height to be flush with the channel at the center of the channel.
According to a further aspect of the invention, the channel may be formed partly in a top plate and partly in a bottom plate. Preferably, the bottom plate contains a weir. Controllably deforming material defining the channel may comprise deforming material of the top plate across from the weir.
According to a further aspect of the invention, there is provided a microvalve, comprising a first plate and a second plate placed together to form a channel between them, a valve seat formed in the first plate on one side of the channel, the valve seat having a valve seat profile, the valve seat profile being U-shaped, deformable material in the second plate opposite to the valve seat, the deformable material being deformable into a deformation profile that matches the valve seat profile; and an actuator positionable against one of the first plate and the second plate for deforming the one of the first plate and the second plate. The microvalve may include a bypass channel is formed in one or both of the first plate and the second plate on at least one side, and preferably both sides, of the valve seat.
According to a further aspect of the invention, there is provided a microfluidic trapping device, comprising a body having a channel extending through the body, the channel having a first end and a second end, a first gate at the first end of the channel, a first gate actuator operably connected to the first gate, a second gate at the second end of the channel and a second gate actuator operably connected to the second gate. Preferably, the body comprises a first plate and a second plate, with the channel being formed between the first plate and the second plate, and the first gate is actuated by moving the first plate towards and away from the second plate. The second gate may be actuated by moving the first plate towards and away from the second plate.
According to a further aspect of the invention, there is provided a method of controlling fluid flow in a channel in a microfluidic flow control device, the method comprising the steps of merging a first fluid stream and a second fluid stream in the channel; and forcing fluid in the first fluid stream into the second fluid stream by repeatedly blocking and unbiocking the first fluid stream. There may also be provided the step of merging a third fluid stream with the first fluid stream and the second fluid stream, the first fluid stream being located between the third fluid stream and the second fluid stream; and forcing fluid in the first fluid stream into the third fluid stream by repeatedly blocking and unblocking the first fluid stream. Preferably, blocking and unblocking the first fluid stream comprises the step of deforming material defining the channel to close a portion of the channel. Preferably, the first fluid stream has a width and the portion of the channel extends widthwise beyond the width of the first fluid stream.
These and other aspects of the invention are described in the detailed description of the invention and claimed in the claims that follow.